The present invention relates to a data imprinting optical system and, more particularly, to a data imprinting optical system capable of imprinting date and other information on the surface of a film used in a camera, for example.
A conventional data imprinting optical system is disposed behind a film. Because the conventional arrangement causes the camera body to become undesirably thick, there have recently been proposed data imprinting optical systems designed to imprint data from the front side of the film.
For example, Japanese Patent Application Unexamined Publication Number hereinafter referred to as "JP(A)"! 4-256918 proposes a retrofocus type data imprinting optical system comprising two lenses. JP(A) 7-104370 proposes a data imprinting optical system wherein an optical axis is bent by a prism. Recently, data imprinting optical systems adapted for panoramic photography have also been proposed in which the image frame size is changed by cutting upper and lower end portions of the film. For example, in JP(A) 6-35061, two lenses are arranged in parallel to each other so as to be selectively used for ordinary photography and panoramic photography. In JP(A) 7-295066, two prisms are arranged in parallel to each other so as to be selectively used for ordinary photography and panoramic photography. In JP(A) 7-287295, a lens is inserted to cause a magnification to change between ordinary photography and panoramic photography.
To provide a data imprinting optical system in front of a film in a camera, it must be disposed in a photographic lens, a finder optical system, an autofocus system, etc. This hinders achievement of further reductions in the size and cost.
In JP(A) 4-256918, the back focus of an objective lens is lengthened to increase the degree of freedom with which a data imprinting optical system can be disposed in a camera or the like. However, the number of constituent members increases, which is disadvantageous from the viewpoint of cost.
In JP(A) 7-104370, the optical axis is bent by a prism to increase the degree of freedom with which a data imprinting optical system can be disposed in a camera or the like. However, the constituent member is larger in size than a lens, which is disadvantageous from the viewpoint of space.
Recently, there has also been proposed a data imprinting optical system that imprints data on a plurality of positions as in panoramic photographs, for example. In this case, extra members and space are needed to effect imprinting on a plurality of positions. JP(A) 6-35061 uses two lenses and hence causes the number of constituent members to increase and also causes the required space to increase, undesirably. JP(A) 7-295066 uses two prisms; therefore, the number of constituent members increases, and the required space also undesirably increases. JP(A) 7-287295 proposes a data imprinting optical system improved in terms of space in comparison to the above two conventional techniques. However, the problem of the increased number of constituent members still remains unsolved.